Dataset Information

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China.

ABSTRACT:

Background

Biomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea.

Methods

A malacological survey of B. straminea was conducted in Guangdong Province, China. Snails were identified using anatomical keys. Water and sediment samples were taken, and their physicochemical properties were analyzed using national standard methods. Landscape and climatic variables were also collected for each site. We compared the environmental characteristics between sites with and without B. straminea using Mann-Whitney U test. We further used generalized linear mixed models to account for seasonal effects.

Results

B. straminea was found at six sites, including one in Dongguan and five in Shenzhen. Probability map found a hot spot of B. straminea distribution at Shenzhen and Hong Kong. Sites occupied by B. straminea were characterized by higher median altitude, mean annual precipitation and moderate temperature. Water with snails had higher median concentrations of total nitrogen, nitrate and nitrites, ammoniacal nitrogen, calcium, zinc and manganese but lower dissolved oxygen and magnesium. Sediments with snails had higher median copper, zinc and manganese. B. straminea was associated with maximum temperature of the warmest month (pMCMC ConclusionsB. straminea is distributed in Shenzhen and its surrounding areas in Guangdong, China. Sites with and without B. straminea differed in the maximum temperature of the warmest month and sediment zinc. Surveillance should be continued to monitor the dispersal of this snail in China.

SUBMITTER: Yang Y

PROVIDER: S-EPMC6217779 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China.

Yang Ya Y Huang Shao-Yu SY Pei Fu-Quan FQ Chen Yue Y Jiang Qing-Wu QW Deng Zhuo-Hui ZH Zhou Yi-Biao YB

Infectious diseases of poverty 20181105 1

<h4>Background</h4>Biomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea.<h4>Methods</h4>A ...[more]

PMID: 30392469

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Project description:BackgroundSchistosomiasis is a snail-borne parasitic disease and is endemic in many tropical and subtropical countries. Biomphalaria straminea, an intermediate host for Schistosoma mansoni, is native to the southeastern part of South America and has established in other regions of South America, Central America and southern China during the last decades. S. mansoni is endemic in Africa, the Middle East, South America and the Caribbean. Knowledge of the potential global distribution of this snail is essential for risk assessment, monitoring, disease prevention and control.Methods and findingsA comprehensive database of cross-continental occurrence for B. straminea was compiled to construct ecological models. We used several approaches to investigate the distribution of B. straminea, including direct comparison of climatic conditions, principal component analysis and niche overlap analyses to detect niche shifts. We also investigated the impacts of bioclimatic and human factors, and then used the bioclimatic and footprint layers to predict the potential distribution of B. straminea at global scale. We detected niche shifts accompanying the invasions of B. straminea in the Americas and China. The introduced populations had enlarged its habitats to subtropical regions where annual mean temperature is relatively low. Annual mean temperature, isothermality and temperature seasonality were identified as most important climatic features for the occurrence of B. straminea. Additionally, human factors improved the model prediction (P<0.001). Our model showed that under current climate conditions the snail should mostly be confined to the tropic and subtropic regions, including South America, Central America, Sub-Saharan Africa and Southeast Asia.ConclusionsOur results confirmed that niche shifts took place in the invasions of B. straminea, in which bioclimatic and human factors played an important role. Our model predicted the global distribution of B. straminea based on habitat suitability, which would help for prioritizing monitoring and management efforts for B. straminea control in the context of ongoing climate change and human disturbances.

Project description:BACKGROUND:Intestinal schistosomiasis due to Schistosoma mansoni was mapped in Cameroon in the 1990s and preventive chemotherapy launched since 2005. A situation analysis conducted in 2011 revealed an increase in schistosomiasis transmission, especially in the equatorial part of the country, despite the fact that Biomphalaria pfeifferi, the main intermediate host of this parasite, is now scarce in many foci. Biomphalaria camerunensis, restricted to the equatorial part of the country, is considered as a less suitable host for S. mansoni due to it resistance to the parasite, although exhibiting a better survival than B. pfeifferi. In a context where human migration is quite frequent as a consequence of terrorism, war in neighboring countries, as well as development of hydraulic projects, it seems appropriate to evaluate the current epidemiological role of B. camerunensis to estimate the risk of extension of S. mansoni distribution in Cameroon. To do this, the susceptibility of three B. pfeifferi and five B. camerunensis populations to a strain of S. mansoni was assessed. Juvenile snails (G1) of each population were infected with S. mansoni miracidia, and prepatent period, infection and survival rates of infected snails, as well as cercarial production were recorded and compared between snail species and populations. RESULTS:Compatibility tests were performed on a total of 827 snails: 344 B. pfeifferi and 483 B. camerunensis. Infection rates were quite heterogeneous, higher in B. pfeifferi (61.5%) as compared to B. camerunensis (7.8%) (Chi-square test: χ2 = 258.88, df = 1, P < 0.0001). All the three B. pfeifferi-infected populations were susceptible to S. mansoni. However, among the five B. camerunensis populations tested, four were susceptible to S. mansoni, with 21.9% as the highest infection rate. The prepatent period was, on average, shorter in B. pfeifferi than in B. camerunensis (P < 0.0001), but the cercarial production was significantly higher in B. camerunensis as compared to B. pfeifferi (P < 0.001). CONCLUSION:These findings indicate that B. camerunensis populations might substantially contribute to S. mansoni transmission and dissemination in Cameroon, their low susceptibility being compensated by their high cercariae production. More attention and surveillance towards this species are required to achieve intestinal schistosomiasis elimination in Cameroon.

Project description:Schistosomiasis is an infectious disease infecting mammals as the definitive host and fresh water snails as the intermediate host. Understanding the molecular and biochemical relationship between the causative schistosome parasite and its hosts will be key to understanding and ultimately treating and/or eradicating the disease. There is increasing evidence that pathogens that have co-evolved with their hosts can manipulate their hosts' behaviour at various levels to augment an infection. Bacteria, for example, can induce beneficial chromatin remodelling of the host genome. We have previously shown in vitro that Biomphalaria glabrata embryonic cells co-cultured with schistosome miracidia display genes changing their nuclear location and becoming up-regulated. This also happens in vivo in live intact snails, where early exposure to miracidia also elicits non-random repositioning of genes. We reveal differences in the nuclear repositioning between the response of parasite susceptible snails as compared to resistant snails and with normal or live, attenuated parasites. Interestingly, the stress response gene heat shock protein (Hsp) 70 is only repositioned and then up-regulated in susceptible snails with the normal parasite. This movement and change in gene expression seems to be controlled by the parasite. Other differences in the behaviour of genes support the view that some genes are responding to tissue damage, for example the ferritin genes move and are up-regulated whether the snails are either susceptible or resistant and upon exposure to either normal or attenuated parasite. This is the first time host genome reorganisation has been seen in a parasitic host and only the second time for any pathogen. We believe that the parasite elicits a spatio-epigenetic reorganisation of the host genome to induce favourable gene expression for itself and this might represent a fundamental mechanism present in the human host infected with schistosome cercariae as well as in other host-pathogen relationships.

Project description:BackgroundSchistosomiasis, also generally known as snail fever, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. In Hong Kong and mainland China, the freshwater snail Biomphalaria straminea has been introduced and has the potential to transmit intestinal schistosomiasis caused by S. mansoni, a parasite of man which has a wide distribution in Africa and parts of the New World, especially Brazil. The first identification of B. straminea in Hong Kong dates back to the 1970s, and its geographical distribution, phylogenetic relationships, and infection status have not been updated for more than 30 years. Thus, this study aims to reveal the distribution and current infection status of B. straminea in contemporary Hong Kong.MethodsSnails were collected from different parts of Hong Kong from July 2016 to January 2017. Both anatomical and molecular methods were applied to identify B. straminea. Cytochrome c oxidase subunit 1 (cox1), internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), and 16S ribosomal DNA (rDNA) were sequenced from individual snails and analyzed. To detect the presence of S. mansoni, both biopsy and PCR analyses were carried out.ResultsUsing both anatomical and molecular analyses, this study demonstrated the existence of black- and red-coloured shell B. straminea in different districts in the New Territories in Hong Kong, including places close to the mainland China border. None of the B. straminea (n = 87) investigated were found to be infected with S. mansoni when tested by biopsy and PCR. The Hong Kong B. straminea are genetically indistinguishable, based on the chosen molecular markers (cox1, ITS1-5.8S-ITS2, and 16S rDNA), and are similar to those obtained in mainland China and South America.ConclusionBiomphalaria straminea is now well established in freshwater habitats in Hong Kong. No evidence of infection with S. mansoni has been found. Surveillance should be continued to monitor and better understand this schistosomiasis intermediate host in mainland China and Hong Kong.

Dataset Information

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China.

Background

Methods

Results

Publications

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China.

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